Paleontologists seek evidence to determine which of the three competing theories - kill, chill or ill - best account for the disappearance of all the large animals at the end of the last ice age.

Thousands of years ago, the earth was populated by giant prehistoric animals, from New Zealand's giant moa, a giant relative of the ostrich, to the ultimate symbol of the ice age, the mammoth. At the end of the last ice age, they died out, but what killed them off? Did humans play a part? Or was it down to environmental causes such as disease or climate change?—Tom Daly